Just a dip, 1000 kills is more like being thrown in at the deep end. Scoreattack is where you want to spend your time. Once you've entered SA, keep voting "none" till you get this map, then choose a game mode. Rinse, Repeat (About 8 times).

Some Killing sprees at 10, 20, 30 ,40 ,50 & 100 and then some Weapon ones at 5, 10 & 15. You might want to jump into some ArcadeFight. Snipers, Shotguns and Swords. 15 kills from each and that's 9 sprees, not including the Killing sprees on the way.

Make a Wish... - Earn a Running Riot in a multiplayer Matchmaking game - 5000cR

This one is the toughy. 15 kills, no deaths. Best bet for this one, Living Dead. Play it smart, get as many kills as you can early on and stay far away from the action.